The European Union urged Russia on Monday to halt its aerial bombing campaign in Syria but the bloc's 28 member states failed to agree among themselves on whether President Bashar al-Assad should have any role in ending the crisis.

Seeking a common front in their criticism of Russia's dramatic military intervention in Syria, EU foreign ministers warned that air strikes designed to support Assad could also deepen the 4-1/2-year civil war that has killed 250,000 people.

Ministers also sought to further pressure Assad by agreeing to broaden the EU's economic sanctions criteria to people benefiting from his government, a move essentially aimed at freezing the assets of the spouses of senior figures, although no names have been added to the EU's list.

"The recent Russian military attacks ... are of deep concern and must cease immediately," ministers said in their most strongly-worded statement on Russia's intervention.

"The military escalation risks prolonging the conflict, undermining a political process, aggravating the humanitarian situation and increasing radicalization," said the ministers, meeting in Luxembourg.

EU leaders are also expected to criticize Russia at a summit in Brussels on Thursday, EU officials say.

After years of inaction in Syria, the EU is now desperate to stem the flow of migrants into Europe. Its stark criticism of Moscow underscores just how far diplomatic efforts have faltered since a U.N. meeting in New York in late September, when Europe and the United States looked to Russia for help.

Russian incursions into Turkish airspace and air strikes directed not at Islamic State militants but at relatively moderate opposition groups have alienated the West, while leaving EU and U.N diplomacy in disarray, diplomats said.